I agree with Scubaman ... Maho, Orient, and Great Bay beach take on a lot of cruise ship visitors. Personally, I like this because it brings the island to life and I've met some really nice people in the past. Best way to avoid cruise ship crowds is to check the port schedule for Philipsburg. It will tell you the number of ship in port in advance each day. Traditionally, the best days with the fewest cruise visitors would be Monday, Tuesday and Friday. Wednesday, Thursday, and Saturday seem to have most most ships in port. And, you can also check out what ships are docking. Some higher end lines like Silverseas and Azamera carry far fewer passengers than those massive ships from Royal Caribbean, Princess, etc.

Anse Marcel and Pinel would likely be a good choice any day of the week, because they simply take too long to get there and get back to the ship on time. Hope this helps!